1. Field of the Invention
This invention relates to the use of hydrocarbyl-substituted polyoxyalkylene amines in fuel compositions to prevent and control engine deposits.
2. Description of the Related Art
It is well known that automobile engines tend to form deposits on the surface of engine components, such as carburetor ports, throttle bodies, fuel injectors, intake ports, intake valves, and combustion chambers, due to the oxidation and polymerization of hydrocarbon fuel. These deposits, even when present in relatively minor amounts, often cause noticeable driveability problems, such as stalling and poor acceleration. Moreover, engine deposits can significantly increase an automobile's fuel consumption and production of exhaust pollutants. Therefore, the development of effective fuel detergents or "deposit control" additives to prevent or control such deposits is of considerable importance and numerous such materials are known in the art.
For example, aliphatic hydrocarbon-substituted phenols are known to reduce engine deposits when used in fuel compositions. U.S. Pat. No. 3,849,085, issued Nov. 19, 1974 to Kreuz et al., discloses a motor fuel composition comprising a mixture of hydrocarbons in the gasoline boiling range containing about 0.01 to about 0.25 volume percent of a high molecular weight aliphatic hydrocarbon-substituted phenol in which the aliphatic hydrocarbon radical has an average molecular weight in the range of about 500 to about 3,500. This patent teaches that gasoline compositions containing minor amounts of an aliphatic hydrocarbon-substituted phenol not only prevent or inhibit the formation of intake valve and port deposits in a gasoline engine, but also enhance the performance of the fuel composition in engines designed to operate at higher operating temperatures with a minimum of decomposition and deposit formation in the manifold of the engine.
Polyether amine fuel additives are also well known in the art for the prevention and control of engine deposits. These polyether additives have a polyoxyalkylene "backbone", i.e., the polyether portion of the molecule consists of repeating oxyalkylene units. U.S. Pat. No. 4,191,537, issued Mar. 4, 1980 to Lewis et al., for example, discloses a fuel composition comprising a major portion of hydrocarbons boiling in the gasoline range and from 30 to 2,000 ppm of a hydrocarbyl polyoxyalkylene aminocarbamate having a molecular weight from about 600 to 10,000, and at least one basic nitrogen atom. The hydrocarbyl polyoxyalkylene moiety is composed of oxyalkylene units having from 2 to 5 carbon atoms in each oxyalkylene unit. These fuel compositions are taught to maintain the cleanliness of intake systems without contributing to combustion chamber deposits.
Aromatic compounds containing a poly(oxyalkylene) moiety are also known in the art. For example, the above-mentioned U.S. Pat. No. 4,191,537, discloses alkylphenyl poly(oxyalkylene) polymers which are useful as intermediates in the preparation of alkylphenyl poly(oxyalkylene) aminocarbamates.
Similarly, U.S. Pat. No. 4,881,945, issued Nov. 21, 1989 to Buckley, discloses a fuel composition comprising a hydrocarbon boiling in the gasoline or diesel range and from about 30 to about 5,000 parts per million of a fuel soluble alkylphenyl polyoxyalkylene aminocarbamate having at least one basic nitrogen and an average molecular weight of about 800 to 6,000 and wherein the alkyl group contains at least 40 carbon atoms.
Also, U.S. Pat. No. 4,270,930, issued Jun. 2, 1981 to Campbell et al., discloses a fuel composition comprising a major amount of hydrocarbons boiling in the gasoline range and from 0.3 to 3 weight percent of a hydrocarbyl poly(oxyalkylene) aminocarbamate of molecular weight from about 600 to about 10,000 having at least one basic nitrogen atom, wherein the hydrocarbyl group contains from 1 to 30 carbon atoms.
U.S. Pat. No. 5,112,364, issued May 12, 1992 to Rath et al., discloses gasoline-engine fuels which contain from 10 to 2,000 parts per million by weight of a polyetheramine and/or a polyetheramine derivative, wherein the polyetheramine is prepared by reductive amination of a phenol-initiated or alkylphenol-initiated polyether alcohol with ammonia or a primary amine.
U.S. Pat. No. 5,660,601, issued Aug. 26, 1997 to Oppenlander et al., discloses fuels for gasoline engines containing from 10 to 2,000 mg per kg of fuel (i.e., 10 to 2,000 parts per million) of an alkyl-terminated polyetheramine, therein the alkyl group contains from 2 to 30 carbon atoms and the polyether moiety contains from 12 to 28 butylene oxide units. This patent further teaches that the polyetheramines are prepared by the reaction of an alcohol with butylene oxide, and subsequent amination with ammonia or an amine.
U.S. Pat. No. 4,332,595, issued Jun. 1, 1982 to Herbstman et al., discloses a gasoline detergent additive which is a hydrocarbyl-substituted polyoxypropylene diamine, wherein the hydrocarbyl substituent contains 8 to 18 carbon atoms. This patent further teaches that the additive is prepared by reductive amination of a hydrocarbyl-substituted polyoxypropylene alcohol with ammonia to give a polyoxypropylene amine, which is subsequently reacted with acrylonitrile to give the corresponding N-2-cyanoethyl derivative. Hydrogenation in the presence of ammonia then provides the desired hydrocarbyl-substituted polyoxypropylene N-3-aminopropyl amine.
U.S. Pat. No. 3,440,029, issued Apr. 22, 1969 to Little et al., discloses a gasoline anti-icing additive which is a hydrocarbyl-substituted polyoxyalkylene amine, wherein the hydrocarbyl substituent contains 8 to 24 carbon atoms. This patent teaches that the additive may be prepared by known processes wherein a hydroxy compound is condensed with an alkylene oxide or mixture of alkylene oxides and then the terminal amino group is attached by either reductive amination or by cyanoethylation followed by hydrogenation. Alternatively, the hydroxy compound or oxyalkylated derivative thereof may be reacted with bis(2-chloroethyl)ether and alkali to make a chlorine-terminated compound, which is then reacted with ammonia to produce the amine-terminated final product.
U.S. Pat. No. 4,247,301, issued Jan. 27, 1981 to Honnen, discloses hydrocarbyl-substituted poly(oxyalkylene) polyamines, wherein the hydrocarbyl group contains from 1 to 30 carbon atoms and the polyamine moiety contains from 2 to 12 amine nitrogen atoms and from 2 to 40 carbon atoms. This patent teaches that the additives may be prepared by the reaction of a suitable hydrocarbyl-terminated polyether alcohol with a halogenating agent such as HCl, thionyl chloride, or epichlorohydrin to form a polyether chloride, followed by reaction of the polyether chloride with a polyamine to form the desired poly(oxyalkylene) polyamine. This patent also teaches at Example 6 that the polyether chloride may be reacted with ammonia or dimethylamine to form the corresponding polyether amine or polyether dimethylamine.
U.S. Pat. No. 5,752,991 issued May 19, 1998 to Plavac, discloses fuel compositions containing from about 50 to about 2,500 parts per million by weight of a long chain alkylphenyl polyoxyalkylene amine, wherein the alkyl substituent on the phenyl ring has at least 40 carbon atoms.